by Michele Chabin, Special for USA TODAY

by Michele Chabin, Special for USA TODAY

JERUSALEM - Rocket fire escalated Monday across the Gaza border as tension mounted over the deaths of three Israeli teens and last week's revenge killing of a Palestinian teenager.

The Israeli army announced it was carrying out airstrikes early Tuesday in the Gaza Strip, calling it Operation Protective Edge.

The airstrikes came after Hamas - the Islamic militant group that controls Gaza - intensified its rocket assault on southern Israel, with more than 60 rockets launched Monday night, the Israeli Defense Force said. One injury was reported.

Israel's Iron Dome, an anti-rocket system developed jointly by Israel and the United States, intercepted 12 rockets over the southern cities of Ashdod and Netivot, but several rockets fell close to Beersheva, the capital of the country's south.

The attacks come after Israel arrested six Jewish suspects Sunday in connection with the young Palestinian's death. Three of the six have confessed to the killing and re-enacted the crime, an Israeli official told the Associated Press. The official spoke on condition of anonymity because of a gag order.

Israel is calling up 1,500 reservists for a potential mission in Gaza, a senior military official announced after Monday's meeting of Israel's security Cabinet, the Jerusalem Post reported. Hamas is not stopping other militant groups from firing at Israel, and its fighters are taking a lead role in such attacks, mostly mortars and rockets, the official said, according to the Post.

Economy Minister Naftali Bennett, head of the right-wing Jewish Home Party, said "all options are on the table. We need to broadcast to Hamas a message of deterrence."

Residents throughout the southern part of the country were instructed to stay close to bomb shelters.

Air-raid sirens sounded as far north as Beit Shemesh, a city between Jerusalem and Tel Aviv in central Israel. Many residents of the center part of the country do not have bomb shelters because, until recently, they were considered to be out of rocket range.

Many residents in Jerusalem and Tel Aviv rushed to clean out shelters, many of which double - illegally - as storage areas.

The increased attacks along the Israel-Gaza border represent a second front for Israel, which has been trying to contain Palestinian rioting in many parts of Israel following last Wednesday's murder of Mohammed Abu Khdeir, 16, whose charred body was discovered in a Jerusalem forest.

His death followed last week's discovery of the bodies of three Israeli teens who were abducted in the West Bank on June 12 and killed.

The six suspects included two brothers, and one of the suspects is the son of a rabbi, the Israeli official said. Three minor suspects were allowed to meet with lawyers Monday, while the primary suspects were not.

Israel's Channel 10 TV said the suspects were the son and five grandsons of a prominent rabbi in Jerusalem, without further identifying him. Israeli officials did not confirm the report.

Rachelle Fraenkel, the mother of one of the slain Israeli teenagers, said that even from the "abyss" of her own pain, she could not describe her distress over the killing of the Arab boy.

"No mother and father should endure what we are going through now. We feel the pain of Mohammed Abu Khdeir's parents," she said.

Israeli Prime Minister Netanyahu spoke Monday with the father of the slain Palestinian teenager, saying "I would like to express my outrage and that of the citizens of Israel over the reprehensible murder of your son."

Emotions were running high in Israel, with multiple reports on social media of angry crowds attacking Arabs in the streets of Jerusalem and tussling with police or anyone else.

Tomer Lavie, an Israeli teacher in Jerusalem, told USA TODAY he witnessed a gang of 20 to 30 young people try to pull a Palestinian taxi driver from his cab.

"I saw the whole thing from the bus on the way home," Lavie said Monday. "They circled a taxi and started cursing at the driver racist slurs."

The youths threatened the driver that they would pull him out if he didn't come out voluntarily, and then one tried climbing through the cab window. Lavie said he called the police, but when they called back they said they didn't find a cab or anyone else in the area.

Most of the youths wore black T-shirts with the logo of an ultra-right-wing Jewish group, Lehava, known for its opposition to mixed marriages and fraternization between Jews and Muslims in Israel, Lavie said.

Whether Hamas will decide to avenge the killings by firing more rockets - including those that can reach central Israeli cities such as Tel Aviv and Jerusalem - could be a source of internal debate, said Jonathan Rynhold, a senior researcher at the Begin-Sadat Center for Strategic Studies at Bar-Ilan University.

"There will be militant elements in Hamas that will be trying to expand the rocket fire and make Israel pay a price for the killings. But there will be others in Hamas who don't want an escalation for their own interests."

If Hamas decides not to broaden the conflict, it could be because Egypt is exerting pressure on it, Rynhold said, because Egypt's anti-Islamist government controls one of the two borders Gazans have with the outside world. Israel controls the other.

Rynhold believes Palestinian President Mahmoud Abbas, whose government rules the West Bank, holds very little sway over Hamas, even though Hamas recently entered into a unity government with Abbas' Fatah party. Hamas, which Israel and the United States consider a terrorist organization, governs Gaza.

"It is hard to imagine Abbas having much leverage over Hamas, given Abbas' condemnation of the kidnapping of the three Israeli teens," an action Hamas applauded, but did not take responsibility for, Rynhold said. The teens were buried the day before Abu Khdeir was murdered. His death is being investigated as a revenge murder.

Kobi Michael, a senior research fellow at the Israeli Institute for National Security Studies, doubts the Palestinians in the West Bank or Israel (which includes East Jerusalem, according to Israeli but not international law) will attempt to launch a third intifada, or uprising.

Although Hamas would like nothing better than to stir up riots, "there is no energy among the Palestinians in Gaza or the West Bank" - the main battlegrounds of the first two uprisings - Michael said. "There are no longer any Jewish settlements in Gaza to rise up against, and Abbas prefers to take his case for statehood to the international arena. That is where the Palestinians, not the Israelis, have the advantage."